New theory on why male, female lemurs same size
When it comes to investigating mysteries, Sherlock Holmes has nothing on Rice University biologist Amy Dunham. In a newly published paper, Dunham offers a new theory for one of primatology's long-standing mysteries: Why are male and female
lemurs the same size?
In most primate species, males ha...
Hidden genitalia in female water striders makes males 'sing'
In a study published in the open-access, peer-reviewed journal PLoS ONE June 10, Chang Seok Han and Piotr Jablonski at Seoul National University, Korea, report that by evolving a morphological shield to protect their genitalia from males' forceful copulatory attempts, females of an Asian species...
Genital stimulation opens door for cryptic female choice in tsetse flies
By snipping off parts of male genitalia and reducing genital sensation in both male and female
tsetse flies, researchers induced a suite of changes in female
reproduction, including reduced ovulation, reduced sperm storage and increased re-mating attempts by the females. "To the best of our knowle...
Sexual harassment from males prevents female bonding, says study
The extent to which sexual harassment from males can damage relationships between females is revealed in a study published today (Wednesday 22 April). Led by the Centre for Research in Animal Behaviour at the University of Exeter and published in Proceedings of the Royal Society B , the research ...
Remembrance of things past influences how female field crickets select mates
RIVERSIDE, Calif. UC Riverside biologists researching the behavior of field crickets have found for the first time that female
crickets remember attractive males based on the latter's song, and use this information when choosing mates.
The researchers found that female
crickets compare the inf...
When it comes to female red squirrels, it seems any male will do
Researchers have found that female
red squirrels showed high levels of multimale mating and would even mate with males that had similar genetic relatedness, basically mating with their relatives.
Researchers from the University of Alberta, in Edmonton, Alberta, Canada and the University of She...
Leiden scientists sequence first female DNA
Geneticists of Leiden University Medical Centre (LUMC) are the first to determine the DNA sequence of a woman. She is also the first European whose DNA sequence has been determined. This has been announced by the researchers this morning, during a special press conference at Bessensap, a yearly me...
Men unaware of their cancer risk when female relatives test positive for BRCA mutation
Men whose mothers, sisters or daughters test positive for a cancer-causing gene mutation also have an increased risk of developing the disease but are unaware of that risk. That is the conclusion of a study at Fox Chase Cancer Center exploring how families communicate genetic test results.
New evidence for female control in reproduction
WASHINGTON, D.C. Adding another layer of competition to the mating game, scientists are reporting possible biochemical proof that the reproductive system of female
mammals can sense the presence of sperm and react to it by changing the uterine environment. This may be the molecular mechanism behi...
X-effect: female chromosome confirmed a prime driver of speciation
Researchers at the University of Rochester believe they have just confirmed a controversial theory of evolution. The X chromosome is a strikingly powerful force in the origin of new species.
Biologists have argued for years whether the X chromosomethe female
chromosome in most animalsplays a spec...
UT Southwestern researchers identify hundreds of genes controlling female fertility
DALLAS Sept. 21, 2007 Researchers at UT Southwestern Medical Center have found nearly 350 genes related to female
fertility. Their research may open the door to much wider study in the poorly understood field of infertility.
This study gives us a way to begin to understand the causes of femal...
Sex is thirst-quenching for female beetles Female
beetles mate to quench their thirst according to new research by a University of Exeter biologist. The males of some insect species, including certain types of beetles, moths and crickets, produce unusually large ejaculates, which in some cases can account for around 10% of their body weigh...
Philandering female felines forgo fidelity
A new cheetah study by the Wildlife Conservation Society and the Zoological Society of London has found that many cheetah litters have more than one father. While promiscuity in the animal kingdom is generally a male thing, researchers for the Wildlife Conservation Society and the Zoological So...
Hearts of male and female rainbow trout are different
The heart is one of the most energy demanding organs of the human body. Its failure to function properly accounts for 600,000 deaths each year. Similarly, the rainbow trout, native to the Pacific Northwest and beloved as a sport- and food fish, requires dynamic and sustained cardiac function to ma...
Male-killing bacteria makes female butterflies more promiscuous
A study at UCL (University College London) finds that a high-prevalence of male-killing bacteria active in many species of insect including the butterfly, actually increases female
promiscuity and male fatigue.
The team found that when the male insect population drops -- killed off by the bacteri...
The sturdier sex? -- Study by Pittsburgh scientists finds female stem cells work better Female
stem cells derived from muscle have a greater ability to regenerate skeletal muscle tissue than male cells, according to a study at Children’s Hospital of Pittsburgh of UPMC.
The study, which is being published in the April 9 issue of the Journal of Cell Biology, is the first ever to repor...
Update on census of world's most endangered cat -- Female Amur leopard found dead
Following the April 18 announcement that only 25 to 34 of the Amur or Far Eastern leopard (Panthera pardus orientalis) remain in the wild, World Wildlife Fund says the number must now be revised because a female
Amur leopard was killed.
Anonymous tips led officers of two leopard anti-poaching sq...
The influence of the menstrual cycle on the female brain
What influence does the variation in estrogen level have on the activation of the female
brain? Using functional Magnetic Resonance Imaging, Jean-Claude Dreher, a researcher at the Cognitive Neuroscience Center (CNRS/Université Lyon 1), in collaboration with an American team from the National Insti...
Temperament linked to onset of cancer and early death in female rats Female
rats that are apprehensive of new experiences as infants maintain that temperament and die earlier from mammary and pituitary tumors than do their more adventuresome sisters, according to new research by a team based at the University of Chicago.
The apprehensive rats were more likely to h...
New technology addresses female fertility preservation
Women at risk for infertility, such as those needing cancer treatment, can freeze mature, fertilized eggs, but the process can take up to six weeks and for some this delay of treatment is not an option.
Immature follicles (the female
egg and surrounding somatic cells) can be preserved at any time...
Older female fish prefer imperfect male mates, study finds
There's hope for the less-than-perfect male ?if you're a swordtail fish, that is. As the size and age of female
swordtail fish increase, so does the preference for males with asymmetrical markings, according to a new Ohio University study.
Molly Morris, associate professor of biological sciences,...
Picky female frogs drive evolution of new species in less than 8,000 years
frogs in a tiny rainforest outpost of Australia have driven the evolution of a new species in 8,000 years or less, according to scientists from the University of Queensland, the University of California, Berkeley, and the Queensland Parks and Wildlife Service.
Looks matter to female barn swallows
Even after they have paired with a male, the female
North American barn swallow still comparison-shops for sexual partners. And forget personality; the females judge males by their looks -- the reddish color of the males' breast and belly feathers.
If the male's red breast is not as dark as other...
The way you eat may affect your risk for breast cancer
...owth factor (IGF-1) in relationship to these two calorie restriction methods chronic and intermittent and tumor development beginning in 10-week old female
mice at risk to develop mammary tumors. Their hope was to explain why intermittent restriction is more effective.
The overall degree of restrictio...
U of M study identifies risk factors of disordered eating in overweight youth
...eased their risk of disordered eating. These findings link different patterns of behaviors and different potential motivators for overweight male and female
adolescents to developing eating disorders.
"Further exploration of these gender differences may be important in understanding who is at highest ri...
Leicester research paves way for first use in Europe of an insect to fight invasive plant
The original work of Dr Bailey established that all the Japanese Knotweed in Britain was octoploid (88 chromosomes) and that only female
plants occurred. Extensive hybridisation was observed to be taking place between Japanese Knotweed and both Giant Knotweed and Russian Vine. The hybri...
Short stressful events may improve working memory
...on of glutamate in the prefrontal cortex of male rodents, which is opposite to the facilitating effect of acute stress, and that estrogen receptors in female
rodents make them more resilient to chronic stress than male rats.
"All these studies should bring new insights into the complex actions of stress ...
Warming climate threatens California fruit and nut production
...fficient winter chill plays havoc with flowering time, which is particularly critical for trees such as walnuts and pistachios that depend on male and female
flowering occurring at the same time to ensure pollination and a normal yield.
Planning for a warmer future
Fruit and nut growers commonly use e...
New research finds possible genetic link to cause of pregnancy loss and disorders
"Where you would normally expect a female
to have eight to 10 pups, there were only one or t...his mutation increased with a mother's age. As the female
mice got older, there was eventually a complete lo...a male with one bad copy of the gene with a normal female
Stuff of stink bombs investigated for role in pregnancy
... relax smooth muscle in the body and it may have a role in inflammation."
"For the past decade, I have studied the role of hydrogen sulphide in the female
reproductive tract. So far, hydrogen sulphide has been shown to relax the uterus and it can be produced by the placenta, uterine tissue and the amniot...
Playing it safe
... constantly produce new sperm. Therefore, they can conceive embryos and become fathers at almost any age - assuming they can find a sufficiently young female
partner. Based on this, researchers have long assumed that cells from the testis have a similar potential as in embryonic stem cells: that is, a pluri...
Male seahorses like big mates
..., clutch, egg and offspring size all increase with female
body size in seahorses, suggesting that males may ...partner body size in mate selection. A total of 10 female
and 16 male sexually mature seahorses, obtained fr...differences in courtship behavior between male and female
seahorses, with choosy males and indiscriminate fe...
Female human embryos adjust the balance of X chromosomes before implantation
...nown in humans, does, in fact, take place in human female
embryos prior to implantation in the womb.
Ms I... male embryos showed hardly any signs of XIST, the female
embryos started to show signs of XIST at the eight...boratory influence the growth rate and survival of female
embryos and whether this can be improved."
Evolution of a contraceptive for sea lamprey
...School of Medicine may lead to a contraceptive for female
lampreys a jawless fish considered an invasive pe.... "Our research could lead to a contraceptive for female
lamprey, providing a method to control their repro... with estrogen action and act as contraceptives in female
lamprey, providing a method to control their numbe...
Lack of happiness hormone serotonin in the brain causes impaired maternal behavior in mice
...ood. However, they needed more sleep during the day and the regulation of their respiration, body temperature, and blood pressure was altered.
mice were able to give birth and produced enough milk to feed their pups, but their impaired maternal behavior led to poor survival of the offspring. ...
Ability to literally imagine oneself in another's shoes may be tied to empathy
... respond to their mental state. These findings could also point to a role of the left hemisphere in empathy.
The researchers also found that in the female
subjects only, the more empathetic people rated themselves, the longer they took to imagine themselves in the position of the person on the screen. Pr...
Size did matter
...with the complex reproductive apparatus of modern relatives of these Cretaceous fossils. The team also came across something of a surprise: two of the female
specimens had inflated cavities that only occur in modern ostracods that have recently mated, meaning fossil evidence for an insemination had been unc...
U of Minnesota-led study finds that hunters are depleting lion and cougar populations
...ese large feline species because replacement males routinely kill their predecessors' cubs to improve their mating opportunities. (Killing cubs forces female
lions into estrus or "heat.") The team of scientists confirmed this effect by comparing the impact of hunting on populations of lions, cougars and leo...
Why do we choose our mates? Ask Charles Darwin, prof says
... population characteristics and the environment and how they work together to produce strong sexual selection, and also what determines whether or not female
choice will evolve in a particular species.
And perhaps the biggest question of all: How does all of this pertain to humans?
"Darwin concluded th...
Stress puts double whammy on reproductive system, fertility
...ufer said, it may be possible to block GnIH to reduce some of the effects of stress on reproduction.
The researchers plan to confirm the results in female
rats and investigate further the role of GnIH in reproduction.